Kratky method of growing vegetables

Kratky hydroponic method of growing vegetables

What is the Kratky System, and what grows best in the Kratky hydroponic method of growing vegetables?  Let find out why you should be growing your greens with the Kratky method.

Kratky method of growing vegetables

The Kratky system, also known as the non-circulating system, is one of the easiest hydroponic systems.

If you ever put a cutting from a plant in a glass of water until it grows roots, then you have seen the basics.

So how did the glass in the windowsill become the Kratky method of growing vegetables?

Dr. Kratky from the University of Hawaii figured out a way to keep plants growing healthy far beyond root starts.

A plant can and will die if submerged in water, and it will actually drown without air. Plant roots need air to be healthy, and the Kratky method allows air to the roots keeping them from drowning.

Best of all, the air to the roots does not require electricity!

When you put a cutting in a bottle of water, it will grow roots. However, if you don’t change the water regularly, the roots will turn brown. This is because the roots have taken much of the air out of the water, and the roots are drowning and will die. You can solve this issue by changing the water often or using the Kratky method of growing.

Dr. Kratky’s method of keeping an air pocket will prevent the roots from rotting.

What is the Kratky hydroponic method of growing vegetables?

The Kratky method solves this problem WITHOUT air stones or pumps, and it is perfect for an off-grid, no electricity situation. See his university of Hawaii study here.

In Dr. Kratky’s method, a plant is stationary above the water line on a board or piece of insulation. The plant is held with some roots submerged and some roots held above the waterline. The stationary board keeps the warm moist air around the roots that are not submerged, allowing them to breathe without drying out. Adding an air stone can be a good idea, but it is not necessary.

Kratky method of growing

The water solution is filled only when you first put your plant in the system. As the plants grow, the air pocket increases, and the water decreases.

The water will run out just as the plants are ready to harvest if all is done well!

This can truly be a set it up and forget it situation.

What vegetables grow best with this system?

These systems are really great for lettuces and greens.

  • All Lettuce
  • Kale
  • Spinach
  • Bok Chou
  • Chard
  • Collard greens
  • Arugula
  • Endive

Some herbs will do well.

  • Basil
  • Mint
  • Dill
  • Cilantro
  • Sage
  • Thyme

What vegetables don’t do well with the Kratky system?

Vegetables that are heavy feeders don’t do well in a Kratky hydroponic system.

The best part of the Kratky hydroponic method is filling it once the plants have enough to grow through the natural cycle of life.

Since you can not always see and test the water solution in this method, it will be too hard to control the right amount of nutrients.

Things I have not had success with using this method

  • Broccoli
  • Brussel sprouts
  • Peppers
  • Tomatoes

Herbs that don’t work well in this system

  • Rosemary
  • Aloe Vera
  • St. John’s wart
  • Chives
  • Lavender

How to grow herbs with the Kratky hydroponic method

The Kratky hydroponic method is designed for use from start to finish of the plant’s life with one fill of water and nutrients. However, I have had a lot of success with herbs that prefer moisture. For example, basil does well, but rosemary prefers drier soil and doesn’t do well in this system.


Herbs in this system will do well only if you keep an eye on the water level. Keep the water level at a level that will keep about half the length of the roots underwater and half in the air.

An important thing to remember is:

Keep an eye on the temperature!!

The number one reason I have seen hydroponic plants struggle is the water gets cold. The temperature should be 72-76 degrees F. Cold water will cause the growth to slow or even stop, and this is easily remedied by heating the water back up.

Put a fish tank heater in your water solution to regulate the temperature without any work. Fish tanks are typically heated to the mid-70s, so it works perfectly in these systems.  Using fish tanks as a basic system can be one of the easiest ways to start with hydroponics.

Keep an eye on the PH.

The easy and cheap way to test is with fish tank test strips. There are many ways to deal with high or low PH and not a concern in single plant bottles. In a bigger system, you should check the PH every month or so.

The best reason to try the Kratky hydroponic method of growing vegetables

The Kratky hydroponic method of growing vegetables is a great way to begin your hydroponic indoor farm.

  • It is super easy to start
  • Almost no work to grow vegetables
  • Total off-grid, no power is needed
  • Can be small enough to fit in any space

I love to grow greens with the Kratky method of growing vegetables, and it is super easy and produces lots of greens.

Try it out, and please let me know your thoughts.


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